The invention relates to the installation of streetlight poles. More particularly, the invention relates to procedures and apparatus for lifting streetlight poles to a vertical position so that the poles may be installed in a mounting hole or on a support stand.
Streetlight poles are made of various materials such as steel, fiberglass, concrete and wood. These poles may range in height from about 20 to 45 feet, or more, and usually taper somewhat from a higher diameter base to a smaller diameter top. The poles typically weigh about 600 to 800 pounds, or more. During the installation of a streetlight pole the pole must be raised to a vertical position, with the lower end of the pole residing at the mounting hole or support stand where it will be located. Numerous issues, not all apparent to the uninitiated, must be addressed in order to raise a streetlight pole in a safe and efficient manner.
One initial issue is that the pole preferably should be raised without utilizing external eyes, lugs, pins, or the like, that are physically attached to the pole. Such attachments are undesirable because of potential interference with the structural integrity of the pole and due to aesthetic considerations.
Streetlight poles also should be raised without the use of support dollies, or the like, that move on the ground. Dollies used for this purpose are problematical due to the uneven terrain often encountered at installation sites and the inconvenience and expense of transporting the dollies.
It is, of course, desirable that the apparatus and method employed to raise a streetlight pole have the capability of raising the pole to a fully vertical position, unlike certain procedures that are unable to do so.
Additionally, it is desirable that when a boom is used to raise the streetlight poles, which is the procedure most often employed, the boom should be operable with minimum vertical clearance. Significant clearance is not always available at the installation site, and working at unnecessary height increases safety concerns.
It is also desirable that any pole lifting and installation operation, and the straps, slings and other apparatus used therein, be universal in their application; i.e., the operation and apparatus should work without substantial modification on a wide range of streetlight pole lengths.
As a significant safety concern, it is desirable that as the pole reaches a vertical orientation, the bottom of the pole should be easily maneuverable by working personnel for positioning in the mounting hole or on the support stand. A procedure that creates a hazardous and/or unwieldy situation is to be avoided at all costs, for example, the hazardous situation where the bottom end of the pole may suddenly break away from ground contact, resulting in a swinging pole that can injure working personnel as it swings or when it once again comes to rest on the ground. Also to be avoided is a situation where the means of attachment of the lifting device to the pole, for example a strap wrapped around the pole using a half-hitch rigging method, slips along the length of the pole, resulting in a dangerous drop in the pole and potential injury to working personnel. This slipping situation is particularly problematic when the streetlight pole has a polished metal or fiberglass surface, and is even more likely when the light fixture(s) is mounted at the top of the pole before lifting, which is usually the case.
Lastly, current streetlight lifting and installation operations often require excessive manpower and simply take too long. For example, the most prevalent current operations that utilize a strap wrapped around the pole with a half-hitch rigging require that a lineman get into a bucket or use a fiberglass stick to remove the strap, an operation that adds five to ten minutes to each operation.
Thus, there is an acute need for a reliable, safe and time-saving method and apparatus for lifting and installing streetlight poles that overcomes the various problems stated above.
The present invention provides an operational procedure and apparatus that safely and quickly raises streetlight poles for installation, while overcoming the problems set forth above.
In one aspect, the invention may be defined as a method utilizing a boom and associated lifting cable, in conjunction with working personnel on the ground, to raise a streetlight pole to a substantially vertical position, and to install the streetlight pole in a mounting hole or on a support stand. The method is carried out by releasably attaching one end of an elongate sling at a point toward the bottom of a streetlight pole, with a portion of the sling proximate the other end thereof being wrapped around the pole at a point above the balance point of the pole. The wrapped-around portion of the sling is releasably attached to the lifting cable. A lifting force is applied via the lifting cable to raise the upper end of the pole off the ground while the lower end of the pole continues to rest on the ground. Upon continued application of the lifting force there is no slippage of the wrapped-around portion of the sling with respect to the pole.
Eventually the pole nears or reaches vertical orientation and the bottom of the pole lifts off the ground, thereby permitting working personnel on the ground to maneuver the lower end of the pole to the mounting hole or support stand.
In another aspect, the invention may be defined as a streetlight pole and releasably attached elongate sling for use, in conjunction with a lifting device, to raise the streetlight pole to a substantially vertical position where working personnel on the ground can safely and efficiently maneuver the lower end of the pole to a mounting hole or support stand. The sling has first and second ends and a length sufficient to span from an attachment point toward the bottom of the pole to a point above the balance point of the pole. The first end of the sling is wrapped around the pole above the balance point of the pole for connecting to a lifting device. Cooperative attachment structures located toward the bottom of the pole and at the second end of the sling releasably attach the second end of the sling to the pole, whereby upon application of a lifting force by the lifting device slack may be eliminated in the length of the sling between the sling first and second ends to prevent slippage of the sling with respect to the pole and to permit raising of the pole to a vertical position where the working personnel on the ground can safely and efficiently maneuver the lower end of the pole to a mounting hole or support stand. The cooperative attachment structures may take the form of an access opening in the pole toward the lower end of the pole and a hook located at the second end of the sling. The sling may include a loop portion at the sling first end connected to a strap portion that extends from the loop portion to the sling second end.